In underground mining operations, many configurations of a toggle and a toggle connection for connecting the conveyor pans of chain scraper conveyors or guide troughs of mining machine guides are known. In mining practice, especially toggle connections in which the toggle in axial extension of the shaft has bolt pins on both toggle heads, the bolt pins, in the coupled state, extend behind bolt areas in the toggle pockets and are secured against laterally falling out of the laterally open toggle pockets. The bolt area on the toggle pockets can comprise bolt bridges rigidly disposed on the toggle pockets or detachable retention elements.
German Patent DE 36 45 321 C2 describes a generic toggle which has a hook-shaped bolt pin disposed on one toggle head and a wider rectangular bolt pin disposed on the other toggle head. On the back end relative to the butt joint, one toggle pocket has a bolt pocket in the form of an undercutting. The toggle pocket engages the bolt hook. The other toggle pocket is open on the back region and ends in an approximately rectangular profile opening of the toggle pocket. In the assembled state, the wider bolt tongue is located in the transition section between the toggle pocket and the profile opening and is secured in place by use of a plate-like swivel bolt which is rounded on both ends of the plate. In the assembled state, one end of the plate is located in a trough which is formed on the side of the toggle pocket that faces the sill of the seam. The other end of the plate is detachably affixed by use of a clamping sleeve to wall projections which are disposed on the lateral wall of the toggle pocket facing the roof of the seam and which have holes for driving in the clamping sleeve. Above its wider bolt tongue, the toggle head has a slot so that no forces can be transmitted to the swivel bolt even when the toggle is engaged in an axial movement, thus preventing an unintentional detachment of the swivel bolt. The lower side of the hook-shaped bolt attachment tapers conically towards the upper side of the bolt attachment, thus allowing the toggle to be attached obliquely to the toggle pocket and to be subsequently swiveled downwardly. The bottom of the two toggle pockets is completely flat. Furthermore, the shoulder areas on the toggle heads and the stop faces on the toggle pockets extend in a straight line diagonal to the longitudinal axis of the shaft, and the shoulder areas of the toggle abut the stop faces without undercuttings.
German Patent DE 100 11 288 A1 describes a toggle and a toggle connection for conveyor pans and guide troughs in which two symmetrically designed toggle pockets are attached to the adjoining ends of the pans and troughs, with the toggle having symmetrically designed toggle heads with bolt tongues. The bolt tongues project with a nearly constant but, relative to the thickness of the toggle heads, considerably lower thickness from the toggle heads. The upper and lower sides of the bolt tongues are plane parallel to one another, and the toggle is prevented from laterally falling out by use of detachable retention bolts on the toggle pockets, with the retention bolts being provided for both bolt tongues. Both retention bolts have two deformable clamping sleeves each disposed on them. The clamping sleeves can be locked in semicircular recesses on opposite wall projections of both long sides of the toggle pockets. Because of the symmetrical configuration of both of the toggle pockets and of the toggles and the retention elements, orientation errors during the assembly can be avoided. The shoulder areas and stop faces run diagonally to the longitudinal axis of the toggle shaft and the toggle pockets and are designed as flat wedge surfaces.
In underground mining operations, the toggles and the toggle pockets are subjected to extremely high wear. The toggle heads of the toggles must absorb all axial forces between neighboring conveyor pans and guide troughs that are generated by the mining machine which travels up and down while changing directions and/or by the passing scrapers of the chain scraper conveyor. At the same time, the toggles and the toggle pockets must ensure a sufficient angular mobility between the adjoining conveyor pans since saddles and troughs in the sill of the seam must be compensated for and since a chain scraper conveyor or a mining machine guide can move only pan by pan or trough by trough.